Torroidal boring head

ABSTRACT

A machine for accurately machining curved holes comprising a rotatable work supporting table having an axis of rotation and a plane of rotation; a segmented torroidal casing having two ends and support means fixedly mounting said casing in a plane parallel to said plane of rotation with the axis of said torroidal casing coinciding with said axis of rotation; a cutting tool rotatably mounted at an end of said casing and having a diameter larger than the diameter of said casing; drive means within said casing operatively connected to said cutting tool, and means to rotate said table about said axis of rotation. A tool for accurately machining a curved hole comprising a segmented torroidal casing having two ends; a cutting tool having a diameter larger than that of said casing, said cutter rotatably mounted at one of said ends; a drive shaft rotatably mounted at the other of said ends; and a gear train mounted within said casing and operatively connecting said drive shaft to said cutting tool.

[ 1 Jan.9,1973

[54] TORROIDAL BORING HEAD [76] Inventor: Elmer D. Blank, 307 ParkwoodDrive, Glendale, Calif. 91202 [22] Filed: Dec. 7, 1970 [21] Appl. N0.:95,868

Related US. Application Data [63] Continuation of Ser. No. 782,818, Dec.11, 1968,

abandoned.

[52] US. Cl. ..408/127, 90/20, 408/71 [51] Int. Cl. ..B23b 29/03 [58]Field of Search ..408/62, 63, 69, 59, 57, 71, 408/125, 127; 82/].4, 1.5;90/18, 20

OTHER PUBLICATIONS Publication: American Machinist; Sept. 14, 1953; pp.139

Primary Examiner-Gerald A. Dost Attorney-Elwood S. Kendrick, Thomas H.Jones and Kendrick and Subkow [57] ABSTRACT A machine for accuratelymachining curved holes comprising a rotatable work supporting tablehaving an axis of rotation and a plane of rotation; a segmentedtorroidal casing having two ends and support means fixedly mounting saidcasing in a plane parallel to said plane of rotation with the axis ofsaid torroidal casing coinciding with said axis of rotation; a cuttingtool rotatably mounted at an end of said casing and having a diameterlarger than the diameter of said casing; drive means within said casingoperatively connected to said cutting tool, and means to rotate saidtable about said axis of rotation.

A tool for accurately machining a curved hole comprising a segmentedtorroidal casing having two ends; a cutting tool having a diameterlarger than that of said casing, said cutter rotatably mounted at one of1 said ends; a drive shaft rotatably mounted at the other of said ends;and a gear train mounted within said casing and operatively connectingsaid drive shaft to said cutting tool.

10 Claims, 3 Drawing Figures PATENTEUJAN 9 1975 SHEET 2 BF 2 INVENTOR D-@A/VK TORROIDAL BORING HEAD This application is a continuation of Ser.No. 782,818, filed Dec. 11, 1968, and now abandoned.

This invention pertains to a machine and to a tool for use therewith inaccurately machining a curved hole.

A variety of machine tools are known and used for machining holes inmetal. To cite but a few, there are milling machines, drill presses, andturret lathes. In these various machines, there is a straight linemovement of the tool into the work being machined, while at the sametime there is relative rotational movement between the tool and thework. The straight line movement of the tool into the work, which is acommon characteristic of machines now in use, produces a straight hole,i.e., a cylindrical hole having straight sides.

Of the various machine tools now in use, none is capable of accuratelymachining a curved hole. By a curved hole, I refer to a hole having theconfiguration of a torus which is a surface generated by the revolutionof a circle about an axis in its plane other than its diameter, i.e.,the axis of the torus or the torroidal axis.

In various structures, such as in missiles or aircraft, the overalldesign requirements of the system may fix rigid design parameters onboth the size and weight of individual elements. When the weight or sizerequirements of a particular element present design problems, it may beadvantageous in many instances to save weight and space by using adesign configuration in which the element contains an accuratelymachined curved hole. Such a design would be completely impractical withpreviously available machine tools because of their inability to machinesuch a hole.

In accord with the present invention, I have provided a machine and atool for use therewith which are capable of accurately machining acurved hole having the configuration of a torus. In accomplishing thisresult, my novel machine employs a rotatable table which supports thework and which rotates in a plane about an axis of rotation. A segmentedtorroidal casing having two ends is fixedly mounted in a plane which isparallel to the plane of rotation of the table with the axis of thetorroidal casing coinciding with the axis of rotation of the table. Arotatable cutting tool having a diameter larger than the diameter of thetorroidal casing is mounted at one end of the casing and is driven by adrive means contained within the casing. During the cutting operation,the table, having the work mounted thereon, is rotated to bring the workinto contact with the rotating cutting too]. As the cutting tool removesmaterial from the work, the work is rotated into the cutting tool suchthat the cutting tool accurately machines a torroidal hole within thework. During the cutting operation, the torroidal hole machined by thecutter encloses the torroidal casing which has a smaller diameter thanthat of the torroidal hole.

My novel tool, as described above with regard to my machine, comprises atorroidal casing having a cutting tool mounted at one end thereof, andhaving drive means contained within the interior of the casing forrotation of the cutting tool.

A specific embodiment of the invention is illustrated in theaccompanying drawings, in which like reference characters designate likeparts in the several views thereof, wherein:

FIG. 1 is a plan view of my machine showing the relation of thetorroidal casing and cutter with respect to the work mounted on therotatable table;

FIG. 2 is a front view of my torroidal boring head in partial sectiontaken along the line 2-2 of FIG. 1, and

FIG. 3 is a top sectional view of my torroidal boring head taken alongthe line 3-3 of FIG. 2.

FIG. 1 illustrates the overall configuration of my machine. A segmentedtorroidal casing 2 subtending an angle of about is mounted on a powersupply takeoff 4, which, for example, may be the output from a verticalmilling machine. A rotatable table 6 is mounted below the torroidalcasing with the plane of rotation of table 6 being parallel to the planeof the torroidal casing 2. The work 8 is fixedly mounted on table 6 andthe axis of rotation 10 of table 6 coincides with the axis of thetorroidal casing 2.

A rotatable cutting tool 12 is mounted at one end of torroidal casing 2,the tool 12 having a diameter larger than that of the torroidal casing.In order to save valuable machining time, it may frequently be desirableto drill out the center portion of the work 8 in approximately themanner shown in phantom line drawing at 13. This can easily beaccomplished by a conventional drill. During the cutting operation, thetool 12 machines a torroidal hole shown in phantom line drawing 16,while the surface 14 of the work advances to approximately the pointshown at line 15 on the torroidal casing 2.

The details of my torroidal boring head are shown in cross-sectionalview in FIG. 3. As shown, a drive shaft 18 is connected through a geartrain within the interior of torroidal casing 2 to the cutting tool 12which is rotatably mounted at the other end of the torroidal cas ing.The torroidal casing 2 may be mounted on a power supply takeoff, asshown at 4 in FIG. 1, by means of bolts which pass through holes 20. Theinner end of drive shaft 18 terminates at an internally splined socket22 which receives an externally splined drive connector 24. Driveconnector 24 in turn engages an internally splined socket 26 of driveshaft 28. The inner end of drive shaft 28 terminates at an externallysplined protrusion 30 on which is mounted an internally splined spiralbevel gear 32. Bevel gear 32 is held on the externally splinedprotrusion 30 by means of a washer 36 and a nut 34 which threadedlyengages the end of protrusion 30.

The drive shaft 28 is rotatably supported within torroidal casing 2 bymeans of tapered roller bearings 46 and 48 and a ball bearing 42. Asleeve 54 surrounds the shaft 28 and holds the inner races of ballbearing 42 and roller bearing 46 in a spaced-apart relationship. Asupport sleeve 38 is mounted within a cylindrical recess 40 of torroidalcasing 2 and supports the outer races of ball bearing 42 and rollerbearings 46 and 48.

The support sleeve 38 has a shoulder 44 which engages the inner surfaceof the outer race of ball bearing 42 and a shoulder 50 which bearsagainst the outer surface of the outer race of roller bearing 46,thereby holding the outer races of ball bearing 42 and roller bearing 46in a spaced-apart relation. The outer surface of the inner race of ballbearing 42 is held relative to shaft 28 by a stop nut 56. Stop nut 56threadedly engages shaft 28 and bears against a gasket 58 positionedbetween the stop nut 56 and the inner race of ball bearing 42.

An annular seal plate fixedly engages the outer surface of supportsleeve 38 and both seal plate 60 and support sleeve 38 are connected totorroidal casing 2 by screws 66, which are in threaded engagement withholes in casing 2. The annular seal plate 60 terminates at an inner lip62 which abuts a spring mounted wiper seal 64 in sliding contact withshaft 28.

The inner surface of the inner race of roller bearing 48 engages theinner surface 52 of gear 32 while the inner surface of the outer race ofroller bearing 48 is held by a retaining ring 68 which is connected tosupport sleeve 38 by a plurality of screws 70 in threaded engagementwith holes in sleeve 38. As illustrated, the shaft 28, gear 32, bearings42, 46 and 48, and the sleeves 38 and 54, are designed such that theycan be assembled into a unit which is then inserted into the cylindricalrecess 40 of casing 2 and held in place by the seal plate 60 and screws66.

The teeth of gear 32 mesh with the teeth of an internally splined spiralbevel gear 72 which is mounted on an externally splined first drivenshaft 74 positioned at about a 90 angle with respect to drive shaft 28.An internally splined helical gear 76 is spline-connected to shaft 74and is driven by rotation of shaft 74 through gear 72. A needle thrustbearing 78 surrounds shaft 74 and contacts the surface of gear 72.Positioned against a thrust plate of needle bearing 78 is a spacersleeve 80 which bears against the inner race of a needle bearing 83.Needle bearing 83 is supported by a sleeve 82 positioned within hole 92in torroidal casing 2 and bearing against a shoulder 85 within hole 92.

A snap ring 87 mounted in sleeve 82 supports the outer race of bearing83. Mounted within sleeve 82 is a needle thrust bearing 84 which bearsagainst the end surfaces of the races of needle bearing 83. An inwardlyextending shoulder 89 of sleeve 82 contacts the outer thrust plate ofneedle bearing 84. A spring mounted wiper seal 88 is positionedoutwardly of shoulder 89 within sleeve 82 while a snap ring 90 holdssleeve 82 in place within hole 92. A plurality of holes 86 in shoulder89 permit the flow of lubricant to wiper seal 88.

An angular contact ball bearing 94 resting on a shoulder 95 rotatablysupports one end of shaft 74. A washer 96 is positioned outwardly ofbearing 94 adjacent a threaded hole 97 containing a threaded plug 98.During assembly, gears 72 and 76 are inserted into the body cavity oftorroidal casing 2 through the end opening which accommodates driveshaft 18 as shown in FIG. 3. After gears 72 and 76 have been insertedand aligned on top of the ball bearing 94, the shaft 74 having bearings78, 83 and 84 mounted thereon together with spacers 80 and 86 and sleeve82 are inserted as a unit through opening 92.

Washer 96 is used in removing bearing 94 as, for example, during repairof the Apparatus. A threaded bolt (not shown) may be inserted into ahole 97 where it encounters the outer surface of washer 96 and forceswasher 96 against bearing 94, thereby removing it from the recess inwhich it is contained.

Gear 76 meshes with a mating helical gear 100 which is internallysplined and engages an externally splined portion 112 of a seconddriven, and shaft which is positioned approximately parallel to saidfirst driven shaft 74. Gear 100 rests on a shoulder 111 and is securedthereto by a retaining ring 108 which engages a washer109. Shaft 110 isrotatably supported by a pair of oppositely positioned tapered rollerbearings and 122, the inner races of which are fixedly held against ashoulder 124 by a lock nut 116 which threadedly engages shaft 110. Locknut 116 has an inner axial groove within which is contained a deformablewedging block 114. The block 114 can, for example, be made of adeformable material such as brass or bronze, and it is locked in placeby a set screw 1 18.

The outer races of tapered roller bearings 120 and 122 are held betweena shoulder 115 and an annular end plate 126 which is connected totorroidal casing 2 by a plurality of screws 128. A spring mounted wiperseal 130 is supported by plate 126 and flexibly engages rotatable shaft110. A tool support ring 132 is connected by screws 134 to the forwardend of shaft 1 10 to provide a bearing surface for the cutting tool 12.

A roller bearing 104 fitted within hole 103 in torroidal casing 2rotatably supports the other end of shaft 110. Positioned outwardly ofroller bearing 104 is a spring supported wiper seal 102 which flexiblyengages shaft 1 10.

The cutting surface 16 generated by the-cutting tool 12 on its contactwith the work is illustrated in FIG. 1. As shown in FIG. 3, the cuttingsurface 16 is larger than the diameter of the torroidal casing 2 suchthat the cutting surface 16 surrounds the torroidal casing 2.

Turning to FIG. 2, the torroidal casing 2 contains a coolant passage andan air passage 142 which terminate respectively in a coolant opening 144and an air opening 146, both of which are in close proximity to thecutting tool 12 (not shown in FIG. 2). On rotation of cutting tool 12the chips are discharged into the space between the cutting surface 16and the outer surface of torroidal casing 2. As illustrated in FIG. 2,the cutting tool is mounted slightly off center with respect to theouter face of torroidal casing 2 such that the center of tool 12 failson the approximate center of the torroidal casing 2 if it were extendedto the cutting face of tool 12.

As illustrated by the foregoing description, the machine and tool of myinvention provide a means for accurately machining curved holes in whichthe diameter of the hole is'relatively large in relation to the radiusof curvature of the hole, i.e., the torroidal radius. Holes which may beaccurately machined in accord with my invention may have, for example, aratio of torroidal radius to hole diameter, i.e., the approximatediameter of the cutting tool, ranging from about 1] 1 to about 2 /1 Inorder to machine curved holes which have a relatively large diameter inrelation to the radius of curvature of the hole, it is necessary thatthe drive means for the cutting tool be relatively stiff and capable oftransmitting high torque. In providing such a drive, it will be notedthat opposed roller bearings 46 and 48 take up axial thrust in eitherdirection on the shaft 28. Similarly, opposed roller bearings 120 and122 take up axial thrust on shaft 1 10.

The gearing employed in the preferred embodiment of my invention isdesigned to carry heavy loads and also to minimize axial thrust exertedon shaft 110 by cutting tool 12. The shaft 110 is driven in acounterclockwise rotation, as shown at E in FIG. 2, by a left handedhelical gear 100 which imparts an axial thrust to shaft 1 10 in thedirection of tool 12. This axial thrust acts to minimize the affect ofany opposite axial thrust imparted to shaft 110 by contact of tool 12with the work.

Shaft 74 is driven in a clockwise rotation (opposite to E as shown inFIG. 2) and drives a right handed helical gear 76 which imparts axialthrust to shaft 110 through helical gear 100. Similarly, spiral bevelgear 72 has a right handed helix while gear 52 has a left handed helixand is driven in a counterclockwise rotation by shaft 28. In thismanner, the outer thrust imparted to shaft 110 in the direction of tool12 and any counter thrust received by shaft 110 on contact of tool 12with the work is transmitted through or absorbed by the entire drivetrain.

The bearing 94 supporting one end of shaft 74 is an angular contact ballbearing which is capable of absorbing axial thrust from shaft 74. Thrustbearing 84 also absorbs axial thrust of shaft 74 while bearing 78absorbs axial thrust imparted by gear 72.

As illustrated in FIG. 3, it should be understood that the interior ofthe segmented torroidal casing 2 contains a lubricant for the elementsof the drive means. The various seals 102, 130, 88, and 64 effectivelyseal the casing against leakage of the lubricant.

Having fully defined a preferred embodiment of my invention in theforegoing specification and drawings, I desire to be limited only by thelawful scope of the appended claims.

lclaim: I

l. A machine for accurately machining curved holes in a workpiececomprising, in combination:

a rotatable table for supporting the workpiece having an axis ofrotation and a plane of rotation;

a segmented toroidal casing subtending an angle of about 90 having twoends and support means fixedly mounting said casing for maintaining saidcasing in a plane spaced from and parallel to said plane of rotationwith the axis of said toroidal casing coinciding with said axis ofrotation;

a cutting tool rotatably mounted at an end of said casing and having adiameter larger than the diameter of said casing;

non-flexible drive means within said casingoperatively connected to saidcutting tool, said drive means including a drive shaft, a first drivenshaft positioned at about a 90 angle with respect to said drive shaft, asecond driven shaft positioned about parallel to said first drivenshaft, gear means interconnecting said drive shaft with said firstdriven shaft and gear means interconnecting said first driven shaft withsaid second driven shaft, said second driven shaft being directlyconnected to said cutting tool; and means to rotate said table aboutsaid axis of rotation for moving said workpiece against said cuttingtool along a curved path coinciding with the toroidal shape of saidcasing.

2. A machine for accurately machining curved holes comprising:

a rotatable work-supporting table having an axis of rotation and a planeof rotation;

a curved casing having two ends, and support means fixedly mounting saidcasing in a plane parallel to said plane of rotation with the axis ofcurvature of said casing coinciding with said axis of rotation;

a cutting tool rotatably mounted at an end of said casing and having adiameter larger than the outer dimension of said casing; drive meanswithin said casing operatlvely connected to said cutting tool andcomprising a gear train including a rotatable shaft supporting saidcutting tool, said shaft being driven by a helical gear which imparts anaxial thrust to said shaft in the direction of said tool, and means torotate said table about said axis of rotation.

3. The machine of claim 2 including a coolant passage and an air passagein said casing, each of said passages having discharge openings adjacentsaid cutting tool.

4. The machine of claim 2 wherein the ratio of the radius of saidtoroidal casing to the cutting diameter of said tool ranges from aboutl/'l to about 2/1.

5. A tool for accurately machining a curved hole comprising:

a segmented toroidal casing subtending an angle of about and having twoends;

a cutting tool having a diameter larger than the diameter of saidcasing, said cutting tool rotatably mounted at one of said ends;

non-flexible drive means within said casing operatively connected tosaid cutting tool including a drive shaft rotatably mounted at the otherof said ends, a first driven shaft positioned at about a 90 angle withrespect to said drive shaft, a second driven shaft positioned aboutparallel to said first driven shaft, gear means interconnecting saiddrive shaft with said first driven shaft and gear means interconnectingsaid first driven shaft with said second driven shaft.

6. The tool of claim 5 wherein the ratio of the radius of said toroidalcasing to the cutting diameter of said tool ranges from about l/ 1 toabout 2/ l.

7. The tool of claim 5 including a coolant passage and an air passage insaid casing, each of said passages having discharge openings adjacentsaid cutting tool.

8. The machine of claim 2 wherein said casing has the configuration of atorus.

9. A tool for accurately machining a curved hole comprising:

a curved casing having two ends;

a cutting tool having a diameter larger than the outer dimension of saidcasing, said cutting tool rotatably mounted at one of said ends;

a drive shaft rotatably mounted at the other of said ends;

a gear train mounted within said casing and operatively connecting saiddrive shaft to said cutting tool, said gear train including a shaft onwhich said cutting tool is mounted, and a helical gear driving saidshaft which imparts an axial thrust to said shaft in the direction ofsaid tool.

10. The tool of claim 9 wherein said casing has the configuration of atorus.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,709,624 Dated January 9, 1.973

Invent0r(s) TOROIDAL BORING HEAD It is certified that error appears inthe above-identified patent and that said Letters Patent are herebycorrected as shown below:

Correct the spelling of the word torroidaP to -toroidal at the followingplaces:

In the title;

Page 1, lines 6, 8 and 15;

Page 2, line 173;

Page 3, lines 3, 5', 8, l5, l6, l7, l8 and 20;

Page 4 lines 2, 4 7, l0, l3, l5 l7, 19, 20

.25 and 28;

Page 5, lines 1, 4, 5, 6, l9 and 24;

Page 6, line LLO;

Page 7, lines 7 and 24;

t me 8, line :22;

Page 9, lines 1, 8 9, ll, l8 20 21, 27 and 29;

Page 11, line 10.

Signed and sealed this 27th day of November 1973 (SEAL) Attest:

EDWARD M.FLETCHER,JR. RENE D. TEGTMEYER Attesting Offlcer ActingCommissioner of Patents FORM PO-lOSO (10-69) USCOMM'DC 60376-F'69 9 U.S.GOVERNMENT PRINTING OFFICE: I969 0-366-334,

1. A machine for accurately machining curved holes in a workpiececomprising, in combination: a rotatable table for supporting theworkpiece having an axis of rotation and a plane of rotation; asegmented toroidal casing subtending an angle of about 90* having twoends and support means fixedly mounting said casing for maintaining saidcasing in a plane spaced from and parallel to said plane of rotationwith the axis of said toroidal casing coinciding with said axis ofrotation; a cutting tool rotatably mounted at an end of said casing andhaving a diameter larger than the diameter of said casing; non-flexibledrive means within said casing operatively connected to said cuttingtool, said drive means including a drive shaft, a first driven shaftpositioned at about a 90* angle with respect to said drive shaft, asecond driven shaft positioned about parallel to said first drivenshaft, gear means interconnecting said drive shaft with said firstdriven shaft and gear means interconnecting said first driven shaft withsaid second driven shaft, said second driven shaft being directlyconnected to said cutting tool; and means to rotate said table aboutsaid axis of rotation for moving said workpiece against said cuttingtool along a curved path coinciding with the toroidal shape of saidcasing.
 2. A machine for accurately machining curved holes comprising: arotatable work-supporting table having an axis of rotation and a planeof rotation; a curved casing having two ends, and support means fixedlymounting said casing in a plane parallel to said plane of rotation withthe axis of curvature of said casing coinciding with said axis ofrotation; a cutting tool rotatably mounted at an end of said casing andhaving a diameter larger than the outer dimension of said casing; drivemeans within said casing operatively connected to said cutting tool andcomprising a gear train including a rotatable shaft supporting saidcutting tool, said shaft being driven by a helical gear which imparts anaxial thrust to said shaft in the direction of said tool, and means torotate said table about said axis of rotation.
 3. The machine of claim 2including a coolant passage and an air passage in said casing, each ofsaid passages having discharge openings adjacent said cutting tool. 4.The machine of claim 2 wherein the ratio of the radius of said toroidalcasing to the cutting diameter of said tool ranges from about 1/1 toabout 2/1.
 5. A tool for accurately machining a curved hole comprising:a segmented toroidal casing subtending an angle of about 90* and havingtwo ends; a cutting tool having a diameter larger than the diameter ofsaid casing, said cutting tool rotatably mounted at one of said ends;non-flexible drive means within said casing operatively connected tosaid cutting tool including a drive shaft rotatably mounted at the otherof said ends, a first driven shaft positioned at about a 90* angle withrespect to said drive shaft, a second driven shaft positioned aboutparallel to said first driven shaFt, gear means interconnecting saiddrive shaft with said first driven shaft and gear means interconnectingsaid first driven shaft with said second driven shaft.
 6. The tool ofclaim 5 wherein the ratio of the radius of said toroidal casing to thecutting diameter of said tool ranges from about 1/1 to about 2/1.
 7. Thetool of claim 5 including a coolant passage and an air passage in saidcasing, each of said passages having discharge openings adjacent saidcutting tool.
 8. The machine of claim 2 wherein said casing has theconfiguration of a torus.
 9. A tool for accurately machining a curvedhole comprising: a curved casing having two ends; a cutting tool havinga diameter larger than the outer dimension of said casing, said cuttingtool rotatably mounted at one of said ends; a drive shaft rotatablymounted at the other of said ends; a gear train mounted within saidcasing and operatively connecting said drive shaft to said cutting tool,said gear train including a shaft on which said cutting tool is mounted,and a helical gear driving said shaft which imparts an axial thrust tosaid shaft in the direction of said tool.
 10. The tool of claim 9wherein said casing has the configuration of a torus.